Single crystals of silicon carbide (SiC) and so on used, for example, as semiconductor materials are often fabricated by a sublimation-recrystallization method. This method is generally carried out by placing raw material powder such as SiC powder and a seed of single crystal in a manner to face each other in a crucible made of graphite or the like and heating them to a high temperature of 2,000 to 2,400 deg. C. in an inert atmosphere.
If, in this case, the crucible made of graphite or the like is used as it is for growing crystal, carbon may sublime from an inner wall of the crucible and give an adverse effect on single crystal growth. It is possible to use a crucible made of a carbide of a high-melting-point metal such as tantalum carbide instead of graphite. Prior art documents generally relating to such a high-melting-point metal carbide are shown below.
Patent Document 1: Japanese Unexamined Patent Publication No. S55-107,751
Patent Document 2: Japanese Unexamined Patent Publication No. S50-80,303
Patent Document 3: Japanese Unexamined Patent Publication No. H06-87,656
Patent Document 4: Japanese Unexamined Patent Publication No. H04-187,739
Patent Document 5: Japanese Unexamined Patent Publication No. H06-87,655
Patent Document 6: Japanese Unexamined Patent Publication No. H10-236,892
Patent Document 7: WO2006/085635
Patent Document 8: Japanese Unexamined Patent Publication No. H06-280,117
Patent Document 9: Japanese Unexamined Patent Publication No. H11-116,398
Patent Document 10: Japanese Unexamined Patent Publication No. 2008-169,111
Patent Document 11: Japanese Unexamined Patent Publication No. 2005-68,002
Patent Document 12: Japanese Unexamined Patent Publication No. H11-116,399
Patent Document 13: Japanese Unexamined Patent Publication No. 2004-84,057
Patent Document 14: Japanese Unexamined Patent Publication No. H08-64,110
Metal carbides, however, are expensive and their bulk sintered bodies are difficult to be processed. Therefore, it is conventionally difficult to produce high temperature-resistant articles comprising metal carbides at low costs. It is also possible to obtain high temperature-resistant articles of complicated shapes by injection molding metal carbide powder. However, injection molding requires a great amount of binder, and removal or burning out of the binder causes defects such as shape deformation or carbon precipitates.
On the other hand, while using graphite or the like as a substrate, it is possible to coat a high-melting-point metal carbide on a surface of the substrate. For example, this is a method in which a high-melting-point metal is vapor deposited or attached on a graphite substrate and then the high-melting-point metal is carburized by heating, thereby forming a metal carbide coating layer on the graphite substrate.
In such a conventional method, however, the high-melting-point metal increases in volume in being carburized and as a result the coating layer is liable to be peeled off due to compressive stress. The coating layer can be formed by CVD, CVR, AIP, reactive ion plating, or other methods, but production costs by these methods are high. It is also possible to carburize only a surface of a high-melting-point metal substrate, but the high-melting-point metal in itself is expensive and difficult to be processed. Besides, since heat resistance depends on properties of a metal as a base material, heat resistance of the surface-carburized high-melting-point metal cannot be as high as that of a metal carbide as a substrate.